The Application Of Qacs To Hab Management And Control

Due to the increasing trend in frequency, scale and impact, the harmful algal bloom(HAB) has caused widespread attention to its management and control, which has been well developed. Nevertheless, there is practically no exploration of direct control of the marine bloom attempting to kill or remove the cells or reduce their toxicity. Quartemary ammoniuin compounds (QACs) are cheap production. By experiments, we find that QACs have good removal effect to Heterosignmt akashiwo and Ske]etonena costa turn. With O.Sppm the removing rate can get 85% in 24h. If the carbon atomicity of QAC main substituent group is between 12 and 18, fewer the carbon is, the removing rate is better and benzyle can improve QAC toxicity. We have tested the change of chlorophyll content, photosynthesis and respiration of their cells to discuss the mechanism of algae removal by QAC. The results indicate that the main reason of QAC destroying algae is that QAC surface adsorption destroys cytomembrane and restraining function of chloroplast etc. The crude clay flocculant can remove HAB without chemical harm. In order to promote the efficiency of clay, We improve it with QACs, and our researchs indicate that the QAC-clay has good effect: With 1 gIL 1 .5CEC QAC-clay, the removing rate rises to 100% from the crude clay 40% in 6h.We think this results from the positive electric charge of improved clay particles, which increases static gravitation of clay and enhances its flocculating Another reason is QAC adsorbed on clay surface poisons the bloom algae, which is propitious to remove HAB by weakening algae activity.